Heavy Residue Production in 215 MeV 16O+27A1 Reactions

Mass, velocity, and angular distributions have been measured for heavy products and for light charged particles from the reaction 215 MeV {sup 16}O+{sup 27}Al. Coincidences between evaporation residues and light charged particles have also been measured. Statistical-model calculations, incorporating light-particle decay from either the compound nucleus or the composite nucleus formed in the direct emission of a beam velocity particle, cannot account for the observed cross sections or angular distributions of the heavy residues. More elaborate kinematic simulations, which include direct light-particle emission as observed in the light-particle inclusive data, also do not work. This supports the notion that heavy fragment production ({ital A}{gt}4) would be needed to account for the residue distributions.